As shown in FIG. 1, a conventional optical sensor module 1 for the use of photoplethysmography (PPG) includes a printed circuit board 11 (PCB) having opposite first and second faces 111, 112, a light-receiver 12 disposed on the first face 111, two light-emitters 13 disposed on the first face 111 and located respectively at two opposite sides of the light-receiver 12, and a light-blocking wall 14 disposed on the first face 111. The light-blocking wall 14 surrounds the light-receiver 12 and the light-emitters 13 and separates the light-receiver 12 from the light-emitters 13. When the optical sensor module 1 is used to make physiological measurement, the light-emitters 13 emit light to irradiate a biological body, and the light-receiver 12 receives the light reflected from or transmitting through the biological body and produces an optical signal representative of a physiological status of the biological body.
Due to material properties or structural thickness of the light-blocking wall 14, the light-blocking wall 14 may be unable to effectively block the light emitted from the light-emitters 13, and the light leaking from the light-blocking wall 14 may interfere with the light received by the light-receiver 12. In addition, because the PCB 11 has poor heat dissipation, temperature deviation in the optical sensor module 1 may affect the results of measurement.